Electrolyte for rechargeable lithium battery and rechargeable lithium battery including the same

Abstract

A rechargeable lithium battery including an electrolyte. The electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2.

What is claimed is: 
     
         1 . An electrolyte comprising:
 a non-aqueous organic solvent;   a lithium salt; and   an additive,   wherein the additive comprises a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2,   
       
         
           
           
               
               
           
         
         wherein in Chemical Formula 1, 
         X 1  is a fluoro group, a chloro group, a bromo group, or an iodo group, 
         R 1  to R 6  are each independently hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and 
         n is an integer of 0 or 1, 
       
       
         
           
           
               
               
           
         
         wherein in Chemical Formula 2, 
         L 2A  and L 2B  are each independently a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, 
         A and B are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and 
         at least one selected from among A and B is a group represented by Chemical Formula A, 
       
       
         
           
           
               
               
           
         
         wherein in Chemical Formula A, 
         R 7  and R 8  are each independently hydrogen, halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group, and 
         wherein the electrolyte is for a rechargeable lithium battery. 
       
     
     
         2 . The electrolyte as claimed in  claim 1 , wherein an amount of the first compound is about 0.2 parts by weight to about 5.0 parts by weight based on 100 parts by weight of the electrolyte for the rechargeable lithium battery. 
     
     
         3 . The electrolyte as claimed in  claim 1 , wherein an amount of the second compound is about 1 part by weight to about 5 parts by weight based on 100 parts by weight of the electrolyte for the rechargeable lithium battery. 
     
     
         4 . The electrolyte as claimed in  claim 1 , wherein an amount of the additive is about 1.2 parts by weight to about 10 parts of weight based on 100 parts by weight of the electrolyte for the rechargeable lithium battery. 
     
     
         5 . The electrolyte as claimed in  claim 1 , wherein a weight ratio of the second compound to the first compound in the additive is in a range of about 0.2 to about 25. 
     
     
         6 . The electrolyte as claimed in  claim 1 , wherein a weight ratio of the second compound to the first compound in the additive is in a range of about 1 to about 5. 
     
     
         7 . The electrolyte as claimed in  claim 1 , wherein Chemical Formula 1 is represented by at least one of Chemical Formula 1-1 or Chemical Formula 1-1, 
       
         
           
           
               
               
           
         
         in Chemical Formula 1-1 and Chemical Formula 1-2, 
         X 1  being a fluoro group, a chloro group, a bromo group, or an iodo group, and 
         R 1  to R 6  being each independently hydrogen, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group, a substituted or unsubstituted C2 to C10 alkenyl group, or a substituted or unsubstituted C2 to C10 alkynyl group. 
       
     
     
         8 . The electrolyte as claimed in  claim 7 , wherein
 R 3  and R 4  of Chemical Formula 1-1 are each hydrogen, and   at least one selected from among R 5  and R 6  is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group, a substituted or unsubstituted C2 to C10 alkenyl group, or a substituted or unsubstituted C2 to C10 alkynyl group.   
     
     
         9 . The electrolyte as claimed in  claim 1 , wherein the first compound is any one selected from among compounds listed in Group 1, 
       
         
           
           
               
               
           
         
       
     
     
         10 . The electrolyte as claimed in  claim 1 , wherein at least one selected from among L 2A  and L 2B  is a substituted or unsubstituted C1 to C5 alkylene group. 
     
     
         11 . The electrolyte as claimed in  claim 1 , wherein at least one selected from among L 2A  and L 2B  is a substituted or unsubstituted C2 to C5 alkylene group. 
     
     
         12 . The electrolyte as claimed in  claim 1 , wherein Chemical Formula 2 is represented by Chemical Formula 2-1, 
       
         
           
           
               
               
           
         
       
       and
 wherein in Chemical Formula 2-1, 
 L 1  and L 2  are each independently a substituted or unsubstituted C2 to C5 alkylene group, and 
 R 21A , R 21B , R 21C , and R 21D  are each independently hydrogen, halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group. 
 
     
     
         13 . The electrolyte as claimed in  claim 1 , wherein the second compound is any one selected from among compounds listed in Group 2, 
       
         
           
           
               
               
           
         
       
     
     
         14 . A rechargeable lithium battery comprising:
 a positive electrode that comprises a positive electrode active material;   a negative electrode that comprises a negative electrode active material; and   the electrolyte for the rechargeable lithium battery as claimed in  claim 1 .   
     
     
         15 . The rechargeable lithium battery as claimed in  claim 14 , wherein the positive electrode active material comprises lithium composite oxide represented by Chemical Formula 3,
   Li x M 1   y M 2   z M 3   1-y-z O 2-a X a , and  Chemical Formula 3
   wherein in Chemical Formula 3,   0.5≤x≤1.8, 0≤a≤0.05, 0<y≤1, 0≤z≤1, and 0≤y+z≤1,   M 1 , M 2 , and M 3  each independently comprise at least one element selected from among metals such as Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr, La, and a combination thereof, and   X comprises at least one element selected from among F, S, P, and Cl.   
     
     
         16 . The rechargeable lithium battery as claimed in  claim 15 , wherein in Chemical Formula 3, M 1  is Ni, 0.8≤y≤1, and 0≤z≤0.2. 
     
     
         17 . The rechargeable lithium battery as claimed in  claim 14 , wherein the negative electrode active material comprises a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, or a combination thereof.